Bill Clinton’s attempt to parse his way out of trouble during the Monica Lewinsky investigation (“It depends upon what the meaning of the word ‘is’ is” and so on) is notorious. There’s less sex, but much more uncertainty about definitions in the latest discussions between the world’s regulators about the correct response to the global banking crisis.

Here’s just a selection of questions posed indirectly in the Financial Services Authority’s latest paper. What is “systemic importance”? Where is the line between “narrow banks” and “casino banks”? What is the optimal level of capital and liquidity for the banking system? What, indeed, is tier one capital? What is “failure”? And, fundamentally, what is the problem?